I utilize a number of assessment tools for pre and post assessment, as well as formative assessment during a workshop or lesson. My standard go-tos based on the activity would be PollEverywhere, Socrative, Survey Monkey and Google Forms. If I am presenting on a specific tool I am sure to use that tool as the form of assessment.
Below is a link to a pre-assessment I conducted in preparation for a training on Google Docs.
Google Docs Workshop Pre-assessment